Dm and Dm3 is a series of locomotives used by Statens Järnvägar (SJ) and later Malmtafik i Kiruna (MTAS) for pulling iron ore trains on Malmbanan in Sweden and Ofotbanen in Norway. A total of 39 double-locomotives (Dm) were delivered between 1953 and 1971, built by ASEA. A further 19 center locomotives (Dm3) were later delivered. Norges Statsbaner of Norway also operated 12 similar locomotives, designated NSB El 12. The Dm is a slower, freight-optimized version of the Da-locomotive.
In the 1980s most of the double locomotive sets were moved other places on SJs network. In 1996 the operation of Malmbanan was transferred to MTAB, who also took over all the triple engines and some of the double engines. They were redesignated Dm2 (for double locomotives) and Dm3 for triple locomotives. From 2000 the new IORE locomotives were delivered, and all the Dm2s and some of the Dm3s were taken out of service. In 2004 one set was donated to the heritage society Malmbanans Vänner, who also owns one El 12. MTAB has announced that they will take the Dm3 out of service by 2011 when enough IORE locomotives are available to relieve them.